The present invention relates to a process and a circuit arrangement for the transmission of data signals with the simultaneous transmission of a radio broadcast between an amplitude-modulated broadcast transmitter and receiver including phase and/or frequency modulation as well as amplitude-modulation of a common carrier.
Such a process is well known from the U.S. Pat. No. 2,808,508 to Sinninger, where a common carrier wave is utilized to transmit and receive an amplitude-modulated audio intelligence and coincidently carries a teletype intelligence by the frequency shift of that carrier wave.
However, to receive that amplitude modulated intelligence with optimum fidelity and minimum distortion, it is desirable to minimize the interference arising during the transmission process between the two intelligences impressed on one common carrier.
According to the Sinninger patent interference is substantially eliminated by the use of an improved radio receiver apparatus, which is adapted to receive a signal carrying intelligences thereon produced both by amplitude and frequency variation, wherein each variable is free of interference or distortion which might be produced by the other.
However, eliminating the interference in accordance with the teachings of the Sinninger patent requires the installation of a new generation of AM-receivers to meet the fidelity requirements related to the above-mentioned transmission process.